1. Field of the Invention
The present invention relates generally to low pressure non-fragmenting rupture disks and assemblies, and more particularly, to non-metallic rupture disk structures having one or more lines of weakness formed by indentations defining blow-out portions therein.
2. Description of the Prior Art
A variety of fluid pressure relief apparatus of the rupturable type have been developed and used heretofore. Such apparatus have generally included a metallic rupture disk which is supported between a pair of supporting members or flanges which are turn connected in a relief connection of a vessel or system containing fluid pressure. When the fluid pressure within the vessel or system exceeds the design rupture pressure of the rupture disk, rupture occurs causing pressurized fluid to be relieved from the vessel or system.
Metal rupture disks have heretofore included one or more scores on a surface thereof which create lines of weakness therein so that upon rupture the disks tear along the lines of weakness. Generally, the lines of weakness define one or more blow-out portions which remain attached to the disks at unscored areas where the disks rupture. Examples of scored metal rupture disks are described in U.S. Pat. No. 3,005,573 to Dodson et al. dated Oct. 10, 1961 (conventional scored rupture disk) and U.S. Pat. No. 3,484,817 to Wood dated Dec. 16, 1969 (scored reversed buckling rupture disk). As described in detail in such patents, the scores formed in the rupture disks are in the form of continuous grooves or indentations in the metal forming the disks.
While non-fragmenting scored metallic rupture disks of both the conventional and reverse buckling types have been utilized successfully heretofore, such use has generally been limited to applications where the fluid pressure at which the disks are designed to rupture is not extremely low. That is, scored metal rupture disks have been unsuitable in extremely low pressure applications, i.e., applications where the disks are designed to rupture at differential pressures in the range of from about 2.5 psi to about 10.0 psi. The reason for such unsuitability is that the metal rupture disks must be extremely thin in order to rupture at such low pressure differentials making the scoring of the disks impossible or impractical.
Thus, there is a need for rupture disks and assemblies containing such disks which are suitable for use in extremely low pressure applications and which are non-fragmenting upon rupture.